1. Field of the Invention
The present invention relates generally to dental implants and more specifically to an improved interlocking implant screw and abutment for retaining a dental implant.
2. Discussion of the Prior Art
There are numerous implant screws and abutments which exist in the field. However, it appears that the junction area between the implant screw and abutment is not specifically designed to reduce micro shear movement. Further, it appears that no implant screw exists which is specifically designed to improve tapping into a jaw bone.
Accordingly, there is a clearly felt need in the art for a an improved interlocking implant screw and abutment with a junction that is specifically designed to reduce micro shear movement, and improve shear strength. There is also a clearly felt need in the art for an improved implant screw which decreases the amount of force required to tap into a jaw bone and which prevents the implant screw from rotating relative to the jaw bone once thereof is installed.
The present invention provides an improved interlocking implant screw and abutment for retaining a dental implant. The implant screw includes a first end and a second end. A drive boss terminates a first end thereof. A first boss is formed below the drive boss and has an outer perimeter which is greater in length than the drive boss. A second boss is formed below the first boss and has an outer perimeter which is greater in length than the first boss. The shape of the outer perimeters of the first and second bosses are preferably round. The drive boss preferably has a hex shape, but may be square or any other appropriate shape. A self-tapping thread is formed on a second end of the implant screw. At least one flat surface is formed along the length of the self-tapping thread. The at least one flat surface decreases the amount of force required to thread the implant screw, because there is less thread cutting surface contacting the jaw bone. The at least one flat surface also provides an area for bone fragments to collect. Further, the jaw bone will form around the at least one flat surface and prevent the implant screw from rotating in its tapped hole. A threaded hole is formed in the first end of the implant screw. The threaded hole is sized to threadably receive an attachment bolt.
The implant abutment includes a first end and a second end. A second boss cavity is formed in the first end of the implant abutment. The second boss cavity is sized to receive the second boss. A first boss cavity is formed on a bottom of the second boss cavity. The first boss cavity is sized to receive the first boss. A drive boss cavity is formed on a bottom of the first boss cavity. The perimeter around the drive boss cavity is greater at a top than at a bottom. The distance across the drive boss cavity at substantially a bottom thereof is preferably the same as the distance across the drive boss such that the outer perimeter of the drive boss contacts the bottom of the drive boss cavity. A counter bore is formed through a second end of the implant abutment to receive the attachment bolt. The attachment bolt is used to attach a first end of the implant screw to the first end of the implant abutment. Walls of the first and second boss cavities provide extra contact area for outer perimeters of the first and second bosses to improve the shear strength of the implant screw relative to the implant abutment.
Accordingly, it is an object of the present invention to provide an improved interlocking implant screw and abutment which increases shear strength between the implant screw and abutment by increasing axial contact area.
It is a further object of the present invention to provide an improved interlocking implant screw and abutment which increases shear strength between the implant screw and abutment by tapering the drive boss cavity.
It is yet a further object of the present invention to provide an implant screw which decreases the amount of force required to form a thread in a jaw bone.
Finally, it is another object of the present invention to provide an improved interlocking implant screw and abutment which provides improved transfer accuracy of the implant abutment pattern to a cap or crown.
These and additional objects, advantages, features and benefits of the present invention will become apparent from the following specification.